Questions on the Jumbo's for the Experts.

[Dittohead]

After reading the excellent threads on the penetration of Long 88's, I was hoping the experts might school me on some of my questions concerning the Sherman Jumbo's. We talk volumes about the German Uber tanks so lets dive into the US Uber tank.

Unfortunately I don't have any good reference material on this beast. Well here goes.

1. From what I remember The Jumbo's were fabricated by welding additional armor onto the body of a standard Shermans. So If I hit a jumbo 20+ times with an 88L56, 75L48 or even a 75L70, would not the non-homogenous armor be more subject to cracking/failure? You see pictures all the time of gouges out of Tiger armor from near penetrations. Never have seen something similar with Jumbo's.

2. Did the Jumbo's have any weak areas similar to the KT.

3. What effect would the additional armor of different quality and BHN have on penetration.

4. I read in the old SL GI anvil victory notes that the 76mm jumbo weren't available until Jan 45. OK OK I know its not the best source, but its all I got. In the game its available Sept 44, at work so I can't check.

Thanks

Tony

[Bullethead]

Dittohead said:

<BLOCKQUOTE>quote:</font><HR>1. From what I remember The Jumbo's were fabricated by welding additional armor onto the body of a standard Shermans.<HR></BLOCKQUOTE>

I don't think so. From what I can gather, both from text and looking at photos, the Jumbo hull was welded up from thicker plates than normal, and the turret, gun mantle, and final drive castings were also thicker than normal. You can see the front upper hull plate edge in most front quarter photos and it's 1 layer, not 2. Also, the heavier gun mantle is quite obvious, as is an extension on the back of the cast turret, apparently a counterweight for the heavier armor on the front.

<BLOCKQUOTE>quote:</font><HR>2. Did the Jumbo's have any weak areas similar to the KT.<HR></BLOCKQUOTE>

Never heard of any in particular. However, the bow machinegun opening would be a problem as with all tanks so armed. Also, the Jumbo's gun mantle was very similar in shape to a Tiger I's, so perhaps there was a chance it deflecting rounds down through the front hull roof. Finally, the sloping rear turret extension would have been a bad shell trap for shots from that direction.

<BLOCKQUOTE>quote:</font><HR>3. What effect would the additional armor of different quality and BHN have on penetration.<HR></BLOCKQUOTE>

I think this is moot because the armor was apparently homogenous.

<BLOCKQUOTE>quote:</font><HR>4. I read in the old SL GI anvil victory notes that the 76mm jumbo weren't available until Jan 45.<HR></BLOCKQUOTE>

No idea.

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-Bullethead

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[Tiger]

JUMBO!! Just used two of these monsters in my last QB. Unfortunately for the computer it only took 1 panzer IV and some armoured cars . Computer did manage to take out my M4 76 sherman though I rarely use jumos though, mainly I play the british when I play the allies. Must be the tea and biscuits.

-johnS

[Bigdog]

Well just killed Jumbo in PBEM QB with 88mm from a Jagd Panther @ 522m head to head in a hull down 1st hit 3rd shot, I got a lower hull penetration & she cooked off. The Jumbo got also 3 shots off & 3 hits 2 ricochets 1 track hit boy I was lucky.

Big Dog

[This message has been edited by Bigdog (edited 09-05-2000).]

[Teamski]

OK, looked up some more info on the Jumbo:

M4A3E2 built for the invasion of France to counter known superior armor and emplacements after finding out that the future M-26 Pershing would not be ready in time. 254 tanks built by Grande Blanc between May and June 1944. Basic Sherman with additional armor to take frontal hull armor to 100mm (4in) and turret to 150mm (6in). Wieght came to 42 (short) tons. All built with basic 75mm gun, some later up-graded to 76's from destroyed tanks. Max speed 22 mph......

All that on one breath!

I would definatley think that Jumbos made it in-theater well before the beginning of 1945

-Ski

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"The Lieutenant brought his map out and the old woman pointed to the coastal town of Ravenoville........"

[This message has been edited by Teamski (edited 09-05-2000).]

[Dixie Diner Six]

From "Sherman - A History of the American Medium Tank":

<BLOCKQUOTE>quote:</font><HR>The protection was improved by welding an additional 1 1/2 inches of rolled armor over the hull front and on the sides of the sponsons. This increased the total thickness in these areas to 4 inches and 3 inches respectively. A heavier differential and final drive housing was cast wiht a maximuim thickness of 5 1/2 inches. The remaining parts of the hull retained the standard M4A3 armor.

A new turret was cast with walls six inches thick on the front, sides and rear...the new gun shield was fabricated by welding a heavy plate to the front of the M62 shield increasing the total thickness to 7 inches.<HR></BLOCKQUOTE>

So it would appear that the turret was a new construction, but the hull and mantlet were original equipment with applique armor. It further states that all 254 conversions were originally armed with the 75. They arrived on the continent in "Fall 1944". Since the mount was very similar, switching to the 76mm was a relatively simple field mod. No dates or numbers are given for the 76mm conversion, but it is noted that in early '45 an additional production run was requested using the 76.

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Let us pass over the river and rest under the shade of the trees

[M Hofbauer]

As a heavy assault tank the Jumbo was intentionally fited with the 75mm gun, because somehow the 76mm wouldn't do HE right (opinions differ on why this was so, some sources state that there was too little or no HE ammo for the 76 (?)).

The official Army order to upgun the M4A3E2 Jumbos to the 76mm gun was issued in March 1945.

I remember very well the discussion I had about this in re. to cc4. When I presented the above info, the other side's argument was that even before that time, as early as late 1944, 76mm Jumbos existed as field conversions, and that the order dating from March 1945 was just an ex post legalization of an already long practiced policy of upgunning the Jumbo. This does sound reasonable.

However, I think it would slightly collide with DDS's post above (because they wouldn't give the official sanctioning of the 76mm Jumbo _after_ they ordered them, it would seem) with the early 45 production order of 76mm Jumbos, unless "early 1945" would mean March 45. Don't misunderstand me, I am not saying one info or the other is right, just stating what I see.

yours sincerely,

M.Hofbauer

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"Do want a game that works???" (CPT Stransky)

[Dixie Diner Six]

I should clarify that the production order for 76mm Jumbos was cancelled as the Pershing was already in full production at the time.

In my reading of it, they came to Europe with 75s, some were upgraded to 76s in the field, this was found to be good and a request was made for more 76s (which was never fulfilled).

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Let us pass over the river and rest under the shade of the trees

[KiwiJoe]

I can testify that Jumbo's do indeed have a weak spot. I had 1 taken out from 700m+ from a 75mm/L48 with a "front hull penetration at weak spot". I presume it was the area around the bow mg.

[Bullethead]

<BLOCKQUOTE>quote:</font><HR>So it would appear that the turret was a new construction, but the hull and mantlet were original equipment with applique armor<HR></BLOCKQUOTE>

Could well be that they were built both ways. I have read both versions, and you know how it seems no 2 Shermans of the same model were exactly alike, with various combinations of old and new features. Could be the prototypes were welded up with extra pieces on a standard hull, to see if the powertrain could handle the new load, and then they switched to thicker plates for production. Can't say for sure. But in any case, the photos I have show the edge of an homogenous front plate.

And no, I'm not cutting up these books just to prove a point. I've done that already; it's somebody else's turn

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-Bullethead

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